Method and system for positioning in a mobile communications network

ABSTRACT

A method and system for obtaining the position of a mobile station located in a current network of a communications system including a plurality of networks supporting different positioning protocols. The current network is identified at a location center based on the identified current network. A suitable positioning protocol is selected among at least two protocols for communication of location information with the current network.

This application is the US national phase of international applicationPCT/SE2002/002308 filed 11 Dec. 2002 which designated the U.S. Theentire content of this application is incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method and system for obtaining theposition of a mobile station in a communications system, and moreparticularly to a method and system for a location service to obtain theposition of a mobile station when located in a current network, whereina home network, an originating network or said current network may usedifferent mechanisms/protocols for positioning signalling between saidnetworks.

BACKGROUND

Positioning is the process of geographically locating Mobile Stations(MS) in a Public Land Mobile Network (PLMN) by collecting and analyzingneeded information, and after calculating the position, reporting it toan application for further usage.

Location-based services are forecasted to be an important feature inmobile communications network. A system for mobile positioning enablesan operator to provide location-based services to its customers.Location information is an important enabler for many of the newservices in the third generation mobile networks. Also, in somecountries there are legal requirements on providing location informationwhen an emergency call is made from an MS.

An ETSI standardised Gateway Mobile Location Centre (GMLC) discloses anexample of a vital part of a mobile positioning system. The GMLC is thelink between the PLMN and location services clients (LCS-C). It receivesthe positioning requests, performs the necessary authentication,initiates the positioning in the PLMN, and sends back the positioninginformation to the requesting application.

The knowledge of the location of a mobile entity opens up a new set ofapplications and enhances existing ones. A number of differentapplications in different fields, such as governmental, operators orcommercial applications are and will be provided.

Each target group has its own demands and needs concerning locationbased services. Governmental use would typically be applicable forpublic welfare such as emergency calls and infrastructure planning.Operators have the ability for more accurate network planning byapplying location information of large groups of mobile users.Commercial applications open up a whole new set of services.

Depending on the type of application it can be run either by an operatoror a service provider. The operator is able to offer service providersaccess to location information, and the operator can also run its ownapplications. Existing services can be greatly enhanced and new servicescan be developed, with the knowledge of the geographical position of amobile entity. The GMLC and a Serving Mobile Location Centre(SMLC)—which collects position information form the communicationsnetwork and calculates the co-ordinates to be used by the applicationallows authorized applications, provided by the operator or thirdparties, to locate an MS using a variety of methods.

One important aspect of positioning is the support for location services(LCS) when mobile subscribers are roaming, i.e when a mobile subscriberis able to travel freely between cells while engaged in a single phonecall, and international roaming, which means that the user can use theoption of taking its phone abroad and using it in a Visited Public LandMobile Network (VPLMN).

Another important aspect is that some applications, for example“friend-finder”-like applications, may need to obtain the position ofMSs which are subscribers of other PLMNs.

Different PLMNs may support different location and roaming locationmechanisms/protocols.

One such roaming location mechanism/protocol, known in the art, is usedwhen the target MS is not located in its home PLMN (HPLMN) and SS7signalling is used between the HPLMN and a VPLMN. In this mechanism theGMLC of the requesting LCS-C first interrogates the HLR (Home LocationRegister) in the home PLMN of the target MS for positioning routinginformation, i.e the current MSC/VLR (Mobile Switching Centre/VisitorLocation Register) address of the MS. Then, this MSC/VLR is interrogatedfor positioning information. The MSC/VLR address can be located in anyPLMN provided that it supports the same SS7 positioning roamingmechanism and that an SS7 roaming agreement exists.

Another approach for a roaming location mechanism/protocol is to use theInternet Protocol (IP). In this mechanism the GMLC of the LCS-C firstinterrogates the GMLC in the home PLMN of the target MS for positioningrouting information, i.e in the PLMN where the MS is currently located.Then, the GMLC of this current PLMN is interrogated for positioninginformation. The MS can be located in any PLMN provided that it supportsthe same IP positioning roaming mechanism.

In addition to the above described methods, there also exist proprietaryroaming support mechanisms and new proprietary solutions can beanticipated to evolve over time due to the consolidation of the numberof PLMN operators.

Thus, there will probably exist various mechanisms/protocols anddifferent operators and vendors will support these in various degrees.Further, when a positioning request is initiated it is not known whichmechanisms will be needed during the course of the location procedure,since this will depend on in which PLMN the target MS is currentlylocated, and the capabilities of that PLMN.

These state of the art solutions require that all PLMNs involved whenpositioning an MS must be able to support the same positioning roamingmechanism/protocol.

As set out above, it is anticipated that this will not be the case.Therefore, it is apparent that interoperability will be seriouslyjeopardized.

Also, it is anticipated that initiated but not successful positioningrequests will create excess traffic load and thereby jeopardize systemperformance.

SUMMARY

It is an object to mitigate the above described drawbacks by providing amethod for a location service requested from an originating network toobtain the position of a mobile station when located in a currentnetwork, wherein said originating network and current network usedifferent positioning mechanisms/protocols. The current network of themobile station is identified, and a suitable positioning protocol isselected: based on the identified current network.

A protocol controller is configured to apply positioning protocols fordifferent communication networks for usage in communication with thenetworks. A processing component is configured to identify the mobilestation's current network, and based on the identified current network,select among said positioning protocols a suitable positioning protocolfor communication with the current network.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description, given by way of example and notintended to limit the present invention solely thereto, will best beappreciated in conjunction with the accompanying drawings, wherein likereference numerals denote like elements and parts, in which:

FIG. 1 illustrates a system according to the invention providinglocation service for positioning a mobile station, wherein anoriginating network and a current network uses different positioningmechanisms/protocols, and

FIG. 2 is a flow chart illustrating the method of positioning a mobilestation according to the invention.

DETAILED DESCRIPTION

With reference now to the figures wherein like or similar elements aredesignated with identical reference numerals, there is a block diagramand a flowchart. This diagram is not necessarily intended toschematically represent particular modules of circuitry or anyparticular data or control paths. It should also be emphasised that theterms “comprises” and “comprising” when used in this specification istaken to specify the presence of stated features, integers, steps orcomponents but does not preclude the presence or addition of one or moreother features, integers, steps, components or groups thereof.

FIG. 1 illustrates one example embodiment of a communication networkconfiguration for providing location services for positioning asubscriber with a portable radio communication apparatus or equipmentsuch as a mobile telephone 1 when located in a current network 6,wherein a home network 5 and the current network 6 use differentpositioning mechanisms/protocols.

The term portable radio communication equipment, which herein after isreferred to as a mobile radio terminal or mobile phone includes but isnot limited to all equipment such as mobile telephones, pagers,communicators, electronic organizers, smart phones or the like.

The system configuration comprises a home Gateway Mobile Location Centre(H-GMLC) 2 and a Serving Mobile Location Centre (SMLC) 3. The GMLC is avital part of a mobile positioning system. The GMLC is the EricssonGateway Mobile Positioning Centre (GMPC), which is Ericsson'simplementation of, but is not limited to, the by ETSI standardisedGateway Mobile Location Centre (GMLC). In one embodiment, the GMLC 2 isa system that comprises at least a computer processor or otherprocessing component and a data store operatively connected to theprocessing component.

The GMLC 2 is the GSM/UMTS PLMN node to be accessed by an externallocation services (LCS) client 4 when it requests the location of acertain mobile station. The GMLC 2 offers interfaces, XML/HTTP based inthis embodiment, through which the LCS client 4, 4′, 4″ and the GMLC 2,2′, 2″ can communicate, for example over an IP network 7, e.g. theInternet. The communication includes positioning requests from the LCS4, 4′, 4″ client and positioning answers from the GMLC 2, 2′, 2″. EachGMLC 2, 2′, 2″ is adapted to handle connections from multiple LCSclients 4, and/or 4′, and/or 4″ simultaneously. Moreover, the GMLC 2performs, among other things, an authorization check on the request.

The authorized request is delivered to the SMLC 3 via a PLMN 5, forexample a GSM network. The SMLC 3 collects position information from theGSM network 5 and calculates the location, such as co-ordinates, to beused by the service or client 4. The location is delivered to the GMLC2, which is adapted to receive the location and create a locationresponse. This response is replied to the requesting LCS-C 4.

The GMLC 2 is adapted to provide support for LCS where position needs tobe obtained for roaming terminals and/or terminals belonging to otherPLMNs 6. The GMLC 2 has information to dynamically select a protocol,SS7 or IP-based in this example embodiment, to be used in thecommunication of positioning data with each specific PLMN 5,6. Thus,based on roaming capability information defined in the GMLC 2 for eachHPLMN 5 and VPLMN 6, the GMLC 2 is adapted to select the proper protocolto be used when addressing the particular PLMN 5,6 with a positioningrequest or routing request.

The GMLC 2 is in this embodiment configured, but not limited, to selectbetween different roaming protocols, for example SS7 based protocols, orIP based protocols such as the GMLC-centric IP roaming protocol orlocation middleware (LMw) centric IP roaming protocols. It shouldtherefore be apparent to those skilled in the art that this technologyis not limited to be employed in an GMLC but could also be located infor example a location middleware. Also, in one embodiment LMw is usedas an interconnect layer between LCS clients and GMLCs. In a suchembodiment, network to network communication may be performed betweenLMw nodes.

One SS7 protocol is defined in the LCS standards Stage 2 GSM TS 03.71, v8.2.0 and GSM TS 29.002 which are enclosed herein by reference. One IPbased roaming protocol is the MLP 3.0.0 developed by LocationInteroperability Forum (LIF) which is enclosed herein by reference.

A flow chart in FIG. 2 illustrates one example method of positioning asubscriber. In step 101 the LCS client 4 sends a positioning request tothe GMLC 2. The GMLC receives the request in step 102, analyses andidentifies the subscriber's home PLMN (HPLMN) 5 in an LCS signallinglist in step 103. Said LCS signalling list comprises entries, eachincluding a network identifier and a protocol. Based on the result fromthe identification and analysis in step 103, a suitable positioningprotocol, for example SS7, is selected for communication with the homePLMN in step 104. A routing information request is sent to the home PLMN5 in step 105 and an answer is received by the GMLC 2 from the PLMN 5 instep 106.

When the GMLC 2 has received the answer it analyses the parameter dataand identifies the subscriber's current PLMN in the LCS signalling listin step 107. In this example the MS 1 is roaming in a visited PLMN 6.Based on the result from the identification and analysis in step 107, asuitable positioning protocol, for example an IP based protocol usingthe IP network 7, is selected for communication with the visited PLMN 6in step 108. A position request is sent to the visited PLMN 6 in step109 and an answer including co-ordinates and/or other locationinformation about the roaming subscriber and its apparatus 1 is receivedby the GMLC 2 from the VPLMN 6 in step 110. Finally, the GMLC 2 createsa position response and replies it to the requesting LCS-C 4 in step111.

The method, system and apparatus are not limited to positioning ofroaming MSs, but are capable of positioning MSs in all cases involvingpositioning related communication between PLMNs. One example of atraffic case where such communication is needed is when an LCS client 4″using an originating GMLC (O-GMLC) 2″ and needs to locate an MS which isa subscriber to another PLMN than an OPLMN (Originating PLMN) 8,independently on whether the MS is roaming outside its home PLMN or not.Another such traffic case occurs when an MS 1 is currently located inits home network HPLMN 5 or a visited network VPLMN 6 but accesses alocation based service, using another LCS-C (4″) associated with anoriginating GMLC (O-GMLC)(2″).

In addition, the invention also extends to computer programs adapted forputting the invention into practice when executed on a computer. Theprogram may be in the form of source code, object code a code suitablefor use in the implementation of the method according to the invention.The program may be embodied for example in a record medium, computermemory, or read-only memory.

Although one example embodiment of the method, system and apparatus hasbeen illustrated in the accompanying drawings and described in theforegoing detailed description, it will be understood that the inventionis not limited to the embodiment disclosed, but is capable of numerousrearrangements, modifications and substitutions without departing fromthe spirit of the invention as set forth and defined by the followingclaims.

1. A method for obtaining the position of a mobile station located in acurrent visiting network of a communications system including aplurality of networks supporting different positioning protocols,comprising: receiving at a location center a positioning request for themobile station; in response to the positioning request, the locationcenter identifying a home network for the mobile station; based on saididentified home network and roaming capability information for the homenetwork, the location center dynamically selecting from among at leasttwo positioning protocols including an SS7-based positioning protocoland an IP-based positioning protocol one of the two positioningprotocols for communication with the home network of locationinformation associated with the position of the mobile station;identifying at the location center the current visiting network of saidmobile station; based on said identified current visiting network androaming capability information for the current visiting network, thelocation center dynamically selecting from among the at least twopositioning protocols one of the two positioning protocols forcommunication with said current visiting network of location informationassociated with the position of the mobile station; sending apositioning request to the current visiting network using the otherpositioning protocol; and receiving positioning information about themobile station from the current visiting network using the otherpositioning protocol.
 2. A method according to claim 1, where beforeidentifying the current visiting network of the mobile station, themethod further comprises: after selecting the one positioning protocolfor communication with said home network, sending a routing informationrequest to the home network, receiving an answer from the home network,and analyzing the answer for identifying the current visiting network ofthe mobile station.
 3. A method according to claim 1, furthercomprising: sending a position information request to the currentvisiting network, and receiving an answer including location informationabout the subscriber from the current visiting network.
 4. A methodaccording to claim 1, wherein the IP-based protocol includes an MLP orIP roaming protocol.
 5. A computer program embodied in a computerreadable medium, comprising program instructions which when executedcause a computer to perform the method of claim
 1. 6. A computer programstored in a record medium, computer memory, or read-only memory andcomprising computer executable instructions which when executed cause acomputer to perform the method according to claim
 1. 7. Apparatus forobtaining the position of a mobile station located in a current visitingnetwork of a communications system including a plurality of networkssupporting different positioning protocols, comprising: a processingcomponent configured to: in response to a positioning request for themobile station, identifying a home network for the mobile station; basedon said identified home network and roaming capability information forthe home network, dynamically select from among at least two positioningprotocols including an SS7-based positioning protocol and an IP-basedpositioning protocol one of the two positioning protocols forcommunication with the home network of location information associatedwith the position of the mobile station; identify the current visitingnetwork of the mobile station; based on said identified current visitingnetwork and roaming capability information for the current visitingnetwork, dynamically select from among at least two positioningprotocols one of the two positioning protocols for communication withsaid current visiting network of location information associated withthe position of the mobile station; send a positioning request to thecurrent visiting network using the other positioning protocol; andreceive positioning information about the mobile station from thecurrent visiting network using the other positioning protocol. 8.Apparatus according to claim 7, further comprising: a receivingcomponent and a sending component, wherein said receiving component isconfigured to receive a positioning request from an location servicesclient, said sending component is configured to send a routinginformation request to the home network, said receiving component isconfigured to receive an answer from the home network, and saidprocessing component is configured to analyze the answer for identifyingthe current visiting network of the mobile station.
 9. Apparatusaccording to claim 7, wherein said sending component is configured tosend a routing information request to the visited network, and saidreceiving component is configured to receive an answer includinglocation information about the roaming subscriber from the visitednetwork.
 10. Apparatus according to claim 7, wherein the IP-basedprotocol is an GMLC-centric IP roaming protocol or a location middlewareIP roaming protocol.